When a 10-year-old girl is found deathly ill from lack of healthy bone marrow, Dr. Connor and the NIH team work feverishly to keep her alive long enough to find a family member who would make a worthy marrow donor. Unfortunately, her adoptive parents just died days before, so Eva makes it her personal mission to find the adrift child's biological mother. But the case's urgency intensifies when others in the same area fall ill from the identical aplastic anemia while Eva struggles to convince the girl's reluctant real mom (as Cyndi, guest star Catherine Wadkins) to help save the abandoned daughter she wants to forget.

Patients at a Maryland hospital face an outbreak of a horrifying "flesh-eating" disease that spreads quickly and continues to kill as Dr. Connor and his elite team desperately thrash around looking for a common cause that could affect so many. Meanwhile a mother frets over her athletic young daughter (as Danielle, guest star Shannon Woodward) who faces a leg amputation. As Dr. Durant conducts tests comparing the patients' blood, Connor buys time with high-powered antibiotics and tries to think outside the box in pin-pointing its unlikely source.